Effects of Spironolactone on Proteinuria of Patients with Type 2 Diabetes

Diabetic nephropathy is the most common cause of kidney failure. We investigated the beneficial effects of spironolactone, alone and in combination with hydrochlorothiazide, on diabetic nephropathy. This randomized clinical trial was conducted on 60 type 2 diabetic patients with nephropathy. The patients were allocated to three groups of 20 to receive spironolactone (50 mg/d) plus placebo, spironolactone (50 mg/d) plus hydrochlorothiazide (25 mg/d), or placebo plus hydrochlorothiazide (25 mg/d). The duration of the study was three months. Measurements of 24-hour urine protein and other markers were performed at start and end of the study. Of 60 patients, 43% were male. The mean age of patients was 56.8 ± 8.3 years. The three groups were homogeneous regarding general factors. At the end of the study, a significant difference in proteinuria was observed between the groups. In the groups that received spironolactone, the mean 24-hour urine protein was reduced (200 mg/24h). However, there was no significant change in the last group. The mean serum potassium in the first group showed a significant increase (0.26 meq/l). However, there were no significant increases in the second and third groups. This investigation showed that spironolactone plus hydrochlorothiazide had a significant effect on reducing proteinuria without causing hyperkalemia and renal failure in patients with glomerular filtration rate > 50 cc/min. Therefore, spironolactone can serve as a renoprotective drug in diabetic nephropathy.